Session Title: Genetics and Genomics of Rheumatic Disease I
Session Type: Abstract Submissions (ACR)
Magnetic resonance imaging (MRI) is ideally suited for detect structural changes and degradation in cartilage against the limitations of radiographic common methods. Changes in volume and thickness are the most widely used variables to measure progression in OA with MRI. The aim of this study is to elucidate the influence of the mtDNA haplogroups on cartilage integrity based on MRI data obtained from different OAI projects.
We analysed the influence of the mtDNA haplogroups on quantitative measurements of cartilage morphology from MRI scans, mean cartilage thickness and volume of cartilage, in the whole knee joint by means of both cross-sectional and longitudinal studies during a follow-up period of 24 months. We selected for analysis 326 patients from project 18 (cross-sectional) and 358 from project 9 (longitudinal), all of them belonging to the progression subcohort of the OAI. Appropriate statistical analyses adjusting by gender, age and body mass index (BMI) at baseline were carried out using SPSS software (v.19) and R 2.10.0 (The R Foundation for Statistical Computing).
The cross-sectional analyses showed that OA patients that carry the mtDNA haplogroup T had increased median values of cartilage volume in medial tibia (2.35×103 mm3 vs 1.95×103 mm3; p=0.009) and medial tibia femoral (3.56×103 mm3 vs 3.02×103 mm3; p=0.015) compartments, when compared with the most common mtDNA haplogroup H. In relation to mean cartilage thickness, OA patients that carry the mtDNA haplogroup T also showed higher mean cartilage thickness in medial tibia, however this difference borderline the statistical significance (1.85 mm vs 1.73 mm; p=0.07).
During the follow-up period of 24 months, OA patients that carry the haplogroup T suffered a significant smaller decline of volume in medial tibia femoral (p=0.015) and central medial femur (p=0.016) compartments when compared with the most common mtDNA haplogroup H. Even when the normalized cartilage volume of these two subregions was analysed, the results obtained were similar (p=0.023 and p=0.031 respectively). In relation to mean cartilage thickness, patients with the mtDNA haplogroup T suffered a significant smaller decline in central medial tibia femoral (weight bearing) (p=0.011), medial tibia femoral (p=0.019), medial tibia (anterior) (p=0.007) and central medial femur (center) (p=0.013) compartments when compared with the mtDNA haplogroup H.
The statistical models applied in the longitudinal approach showed both age and gender (female) as risk factors for volume loss (p<0.02 and p<0.0001 respectively) and thickness loss (p<0.05 and p<0.0001 respectively) in articular cartilage over time.
The mtDNA haplogroups manifest an intrinsic relation with OA progression in terms of cartilage integrity; carriers of this mitochondrial variant show a slower disease progression than haplogroup H carriers (most common in Caucasian population). The early haplogroup assignment could be crucial for an effective follow-up of the disease and a fit treatment.
M. E. Vázquez-Mosquera,
F. J. Blanco,
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ACR Meeting Abstracts - https://acrabstracts.org/abstract/the-mtdna-haplogroups-influence-the-cartilage-integrity-in-osteoarthritis-data-from-the-osteoarthritis-initiative-oai/